Sleep-wake patterns of intact and carotid sinus nerve sectioned rats during hypoxia.

Six male rats breathed 21 an 10% O2 before and after carotid sinus nerve (CSN) section. Polygraphic recording techniques were used to monitor sleep and wakefulness. The effects that these gas mixtures had on the rats' sleep-wake pattern (SWP) were studied. The SWP of CSN sectioned rats breathing 21% O2 was unchanged compared with that of intact rats. While breathing 10% O2, the intact rats' SWP was altered dramatically. Paradoxical sleep (PS) was absent on the first day's exposure to hypoxia. After CSN section, the SWP approximated that of rats in normoxic conditions. The amount of PS increased considerably. It is concluded that the peripheral chemoreceptor reflex pathway contributes, in part, to disruption of the SWP under hypoxic conditions, but not under normoxic conditions. Mechanisms underlying changes in states of consciousness due to hypoxia are discussed.